Advances in knowledge from the Human Genome Project have the potential for helping reduce cancer incidence, but may also pose difficulties in interpretation by laypersons. The primary objectives of the proposed research are: 1) to investigate beliefs about genetic and lifestyle-behavioral factors in the causation of cancer among mid-adolescents and adult family members, and 2) to evaluate the effectiveness of a brief educational intervention for increasing understanding of the multifactorial nature of cancer causation. Following a pilot study, 120 15-year-olds and one to three members of their households will be recruited by newspaper advertisements to participate either in their homes or in a newly available university laboratory. Two recently developed scales, the Beliefs About Health Risks questionnaire and the Cancer and Genetics Survey, and a numerical estimation procedure demonstrated to be sensitive to beliefs about synergistic effects, will be used to assess how the members of each household group perceive health risks, especially the extent to which they view risks as unitary versus multiple, interacting, and potentially modifiable through appropriate health behaviors. The similarity of the adolescents' health beliefs to those of family members and peers will be described and the relative strength of these influences will be compared. A repeated measures design will be employed to study the effects of a combination didactic and audiovisual intervention targeted to increase understanding of gene-behavior interactions in disease and the need for preventive behaviors; a control group will receive a tobacco-oriented presentation without the focus on genetics. A three-month follow-up will be conducted by phone, including evaluation of whether the family has begun to keep a family tree with health information and whether the adolescents have increased their knowledge of health problems among parents and grandparents. Results will also be explored for patterns associated with age, gender, and ethnicity using hierarchical linear modeling. The information is of relevance for enhancing educational and media-based strategies for increasing appropriate health behaviors, as well as for design of future research and development of models relating health behavior to cognitive processing of causal information. The data may be of use to community organizations, school psychologists, teachers, physicians, and public health officials who communicate health information to adults and adolescents during a stage of increasing independence in decision-making.